Centrifugation Rotors

Fig. 10. (a) Forming a gradient and (b) applying the sample to the gradient before inserting tubes in a centrifuge rotor. 

Stress in the Centrifuge Rotor The stress in the centiifuge rotor is quite complex. Analytical methods, such as the finite element... 

Transfer powder into a 50-ml Falcon-style tube, measure the volume of powder, and add an equal volume of lysis buffer to suspend cell proteins in buffer. Centrifuge at 3500 Xg (4000 rpm in a Sigma 4K15 centrifuge, rotor 11150) for 5 min at 4° to pellet the cell debris. 

Centrifuge the supernatant in a 50-ml polycarbonate tube (Beckman) at 18,000X (12,250 rpm in a Heraeus Biofuge Stratos centrifuge, rotor 3335) for 15 min at 4°, and collect the clarified lysate. 

In a centrifuge rotor g ax is the maximal centrifugal force at maximal distance from rotor axis r ax (at the bottom of the tube), gmin is the minimal force at the top of the tube (rmin), and the arithmetic mean of both is called gav The difference of r ax and rmin is the sedimentation path length. 

Tabletop centrifuge, rotor, and 50- to 500-ml tubes, or sintered glass funnel Whatman No. 1 filter paper in a Buchner funnel Separatory funnel Rotary evaporator...

Apparatus for analytical ultracentrifugation, (a) The centrifuge rotor and method of making optical measurements. (b) The optical recordings as a function of centrifugation time. As the light-absorbing molecule sediments, the solution becomes transparent. 

Figure 1. Density profile in the cell of the ultracentrifuge in case of standard and rapid density gradient centrifugation (rotor speed N = 40.000 min 1)...

Each ribosome consists of two subunits, a small subunit and a large subunit, each of which is a multicomponent complex of ribosomal RNAs (rRNAs) and ribosomal proteins (Fig. 1). One way of distinguishing between particles such as ribosomes and ribosomal subunits is to place the sample in a tube within a centrifuge rotor and spin this at very high speed. This causes the particles to sediment to the tube bottom. Particles that differ in mass, shape and/or density... 

Boone et al. (1968) centrifuge cells through a discontinuous 10-20% Ficoll gradient made up in Eagle s minimum essential medium modified for suspension (i.e. lacking calcium and bicarbonate and containing 10 times the normal phosphate concentration). They use an A-1X zonal centrifuge rotor and spin for 1 h at 1000 r.p.m. at 20°C, and obtained clear separation of different cell types (HeLa and rabbit thymocytes). 

Both cyclones and centrifugal rotor devices remove particles of larger aerodynamic diameter by impaction induced by abrupt changes in aerodynamic flow lines, followed by collection of the liquid water out of the flow stream. Coarse aerosol particle (> 2.5 pm diameter) distributions usually overlap the lower end of cloud droplet distributions, hence are removed to a substantial extent in the... 

The considerations used to calculate the RCF exerted on a sample spinning in a centrifuge rotor require that the sample be located at a fixed distance, r, from the center of rotation. Owing to rotor design, r varies from top to bottom of the sample holder. The problem is illustrated in the following example. 

Transfer the filtrate to centrifuge tubes. Be sure each pair of centrifuge tubes is carefully balanced (use a Harvard triple-beam balance) before they are placed in a centrifuge rotor. 

---